ARES, atmospheric relaxation and electric field sensor, the electric fieldexperiment on NETLANDER

The conditions which prevail in the atmospheres of most planets in the Sola r System, in particular the telluric ones, are likely to give rise to their electrification The resulting processes, which are of major importance for meteorology and climatology on Earth, may also be significant for atmosphe ric and surface processes on the other planets and specifically on Mars. We first review the fundamental parameters and mechanisms of interest for atm ospheric electricity in the Martian environment and discuss in more detail the contact electrification of dust particles, raised and transported by th e wind, which is expected to be the most efficient charging process. We the n briefly describe the Martian global electrical circuit, and the anticipat ed features of DC and AC electric fields, their role in other domains, such as dust transport and surface chemistry, and the possible existence of low -frequency AC electric fields originating from the more distant ionized env ironment. Ln the last part, we present the ARES experiment that we wish to fly on the NETLANDER mission and the main features of the instrument design . (C) 2000 Elsevier Science Ltd. All rights reserved.